2000 Boxster S Check Engine Light Diagnosis

[black_box]

Hi everyone,

I bought a 2000 Box S this spring with 89k on the clock, but with a replaced engine with a theoretical 30k on it. As far as I know it's all stock.

I put a TON of miles on the car this summer (now at 104k) and really love it, but it's having some hiccups.

Sometime in July, it began throwing a CEL with a catalyst below limit code occasionally right after startup with a cold engine. I would clear it by pulling the engine computer fuse and replacing and it would stay off for a few weeks no problem.

A few weeks ago, I got caught in a really bad rain / flash flooding situation. I had to drive through some pretty nasty puddles and other cars were splashing me hard. I believe some water must've gotten into my ignition system. It began misfiring badly and would stumble under any load, but then drove fine after being left to sit and dry out for 10-15min. The code showed a misfire on cylinder 6.

I am afraid this may have accelerated whatever was causing the CEL to pop up before. The problem has gotten worse and it's now throwing the catalyst code every time I get in to drive. Before I start replacing a bunch of stuff, I'd like to put together a plan to isolate the fault and correct it. I will have access to a lift soon and want to pull the cats and 02 sensors for inspection, as well as checking the ignition wiring for cracks and probably replacing plugs / oil / filter while I'm at it.

I have a feeling that the cat(s) may have gotten burned up - will removing them and shaking detect that type of degradation? Anyone used a universal replacement cat before on this car? I am thinking of replacing the primaries with a magnaflow or similar and deleting the secondaries.

Anyone have any experience with this type of issue or have any suggestions as to how to track down the problem?

[Loren]

We really need all the faults codes currently on your car. Without them everything is just a wild guess.

[JFP in PA]

Anyone have any experience with this type of issue or have any suggestions as to how to track down the problem?

Yeah, get the car scanned and post the codes................ It is impossible to even hazard a guess as to what the problem is without the codes.

Edited October 5, 2011 by JFP in PA

[black_box]

I'll get it scanned this afternoon. Thanks for the quick replies!

[black_box]

Well, turns out it wasn't on bc of cat this time.... It showed P0410 and P01411, which are both due to air injection system, which explains the cold engine condition at time of cel coming on. I will check fuse for air pump and for vac leaks.

[Loren]

P0410 Secondary Air Injection System, Bank 1 – Below Limit

P1411 Secondary Air Injection System, Bank 2 – Below Limit

Possible causes:

- Secondary air injection pump is not triggered

- Secondary air injection pump does not function

- Air supply lines restricted

- Electric change-over valve does not function

- Air change-over valve does not function

- Vacuum system leaking

[black_box]

After I verify that everything is connected and that the fuses are good, I will do a water bottle vacuum leak test when I can get the car up on a lift.

[JFP in PA]

A common cause for these codes is the change over valve; sometimes they just start to stick, but usually they are not fixable. If you have access to a PIWIS or Durametric system, I think you can actually test the valve without removing it.